Internal-combustion engine.



.W. J. WRIGHT.

INTERNAL COMBUSTION ENGINE. APPLIOATION FILED APR. 10, 1911. RENEWED MAR. 14, 1913.

1,076,090 Patented 0t.21,1913.

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' INTERNAL COMBUSTION ENGINE.

APPLICATION FILED APR. 10, 1911. RENEWED MAR. 14, 1913.

1,076,090, Patented 0015.21, 1913.

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Patented Oct. 21, 1913.

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Patented Oct. 21, 1913.

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INTERNAL COMBUSTION ENGINE. APPLICATION FILED APR.10, 1'911. RENEWED MAR. 14, 1913.

1,076,090, Patented Oct. 21, 1913.

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Patented Oct. 21, 1913.

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WILLIAM J". WRIGHT, OF FRANKLIN, "PENNSYLVANIA, ASSIGNOR T0 WRIGHT ENGINE COMPANY, OF PITTSBURGH,PENNSYLVANIA, A CORPORATION OF DELAWARE.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

' Patented Oct. 21, 1913.

Application filed April 10, 1911, Serial No. 620,071. Renewed March 14, 1913. Serial No. 754,356.

To all whom it may concern:

Be it known that I, WILLIAM J. WRIGHT, residing at Franklin, in the county of Venango and State of Pennsylvania, have invented certain new and useful Improvements in Internal-Combustion Engines, of which the following is a specification.

My invention is an internal combustion engine of the compound type and it employs a set or sets of parts including a high pressure cylinder and its piston operating generally on the two-cycle principle; a low pressure cylinder and its piston operating generally on the two-cycle principle under the influence of a charge admitted thereto from r the high pressure cylinder, a pump to cause the Working agent to flow into the high pressure cylinder; and means for causing the heat to be periodically drawn out of the cylinder walls and residual charges and its expansion force utilized.

My invention also includes means for cooling the valve that is located between the high and low pressure cylinders just prior to and also at the time of the firing of,the new mixture thereby also cooling the new charge and increasing its density so that a greater initial pressure at the instant of firing the charge is had with a corresponding increase of work onthe high pressure piston.

My invention also has for its object to provide an engine wherein the-cylinders may be cooled, or in other words, wherein the heat in the cylinder walls may be drawn out andused to assist in operating the engine, there-- by increasing the efliciency of the machine.

Again itis the object of my invention to provide means whereby a maximum initial density of the new mixture may be obtained prior to ignition so that the initial pressure of the fired mixture will rise to a maximum. In other words, by combining pressure and simultaneously cooling the new charge and the cylinder walls, a maximum density of working agent is obtained, and thereby the force of expansion when ignition takes place Will be considerably, greater than has been heretofore found possible in engines of the internal combustion type. Furthermore insteadof the heat of combustion being diffused throughout the cylinder walls and its energy lost through conduction and radiation and overheating of the moving parts, such heat is drawn out of the engine walls, etc. by the air charge, thereby causing the air to expand and do work.

In its morespecific nature the invent-ion also resides in those novel details of construction, combination and arrangement of parts, all of which will be first fully described and then be specifically pointed out in the appended claims, reference being had to the accompanying drawings, in which:

Figure l, is an end elevation of my invention. Fig. 2, is a top plan view looking directly down on one set of cylinders, thereby showing the other set of cylinders in elevation. Fig. 3, is a cross section on the line 3-3 of Fig. 2, looking in the direction of the arrow. Fig. 4, is a' section on the line 4-4 of Fig. 1. Fig. 5, is a section on the line 55 of Fig. 1, (by connecting the lines AB, of Figs. 4: and 5 and holding the sheets at an angle of 90 with one another, the two views may be read together). Figs. 6, 7, 8, 9, 10, 11 and 12 are diagrammatic views of the engine showing the relative position of parts at the same time.

Referring now to the accompanying drawings in which like letters and numerals of reference indicate like parts in all of the figures 1, 2, 6 and 7 designate the high pressure cylinders and 3, 4, 8 and 9 designate the low pressure cylinders. Each engine unit includes a high and a low ressure cylinder, the cylinders 1 and 3 being included in one unit, the cylinders 2 and 4 in another unit, and so on.

5 and 10 designate the fuel pumps, the pump 5 being a double-acting one and supplying the cylinders 1 and 2, While the pump 10 supplies the cylinders 6 and 7. Each engine unit thus includes a high, pressure cylinder. and its piston, a low pressure cylinder and its piston and a charging pump (one half of the double-acting pump in the present case).

of the low pressure cylinders, while 12 desig nates the exhaust valves of the same. The high and low pressure cylinders are joined together by a conduit 13 that opens up at 14 into the respective low pressure cylinders and communicates with the high pressure cylinders through intercommunicating valves 15. The high pressure pistons are designated by the numeral 16 and the low pressure pistons are designated by the numeral 17. Each high pressure cylinder has a set of piston controlled air inlet ports 18 about midway its ends and located at the lowermost extremity of the respective combustion chambers.

19 designates air pumps in which pistons 20 operate, the pistons 20 being joined by piston rods 51 with the low pressure piston 17, the piston rods 51 passing through suitable glands 52 in the cylinder heads.""Each piston 20 has a longitudinal bore 21 that merges in an outlet port 22 which is adapted to register at times with the port 23 in the wall of the pump casing 19.

24 is a pipe that joins the port 23 with the duct 13 in the head of the high pressure cylinder at a point opposite to the low pressure cylinder opening 14 for a purpose hereinafter more clearly apparent.

25-25 are back check valves in the pipes 24. The pump 19 has an inlet 28 that communicates with the air inlet pipe 26 through a back check value 27. Each gas pump 5 and 10 has its pump cylinder closed ended and contains a piston 30 that divides the cylinder into an upper and a lower pumping chamber. Each piston 30 has a longitudinal duct 31 leading in from the upper end of the piston and merging with a port 32 that is adapted at times to register with one of the ports in the pump cylinder that communicates with the high pressure cylinder 2 through the pipe 36 in which is contained a back check valve 37. Each pump piston 30 also has a duct that leads from its bottom end to a lateral port 34 which is adapted at times to register with one of the ports 35 of the pump cylinder with which the pipe 36 having a back check valve 37 communicates to convey the charge to the port 38 that opens into the high pressure cylinder 1.

The charge of working agent is admitted to the pump 5 at each end through pipes 10 from the source of working agent supply, the pipes 4,0 having back check valves 39 for the usual purpose. The cylinder of each pumpj'j5' and 10 respectively is mounted 011 a cross head guide 41 in which the cross head 42 operates. The cross head 42 is connected with the piston 30 by a connecting rod 43, as

indicated. The crank shaft 44 has cranks 45 which are connected through rods 48 with the respective high pressure pistons 16 and it has other cranks 16 which connect through rods 49 with the respective low pressure pis-- tons, additional cranks 47 being provided, with which the cross heads 42 are joined through connecting rods 50.

In building my engine, I make a tubular crank case 5-1l and provide it with large bearings for the crank shaft. The crank shaft 44 is preferably constructed as set forth in my copcnding application filed on October 14-, 1910, Serial No. 587,058, and the bearings have bearing balls and races preferably of the construction shown in my copending application filed October 12, 1910, Serial No. 586,747. In this application I lnake no claim to the construction of the shaft and the bearings par 80, as such form the subjectsmatter of my copcnding applications above referred to, and therefore a detailed description and disclosure of the same in this application is thought to be unnecessary.

Each low pressure cylinder has a flange 57 through which it is connected to the crank case 54, the flange 57 having an extension 58 bored to receive the lower end of the high pressure cylinder of the set, the bore being slightly elongated to allow for expansion and contraction of the parts.

The extreme heat in the high pressure cylinder causes greater expansion in that cylinder at the combustion chamber end and thereby moves-the axial line of the high pressure cylinder farther away from the axial line of the low pressure cylinder while the engine is running than the position it assumes when the engine is at rest. If the connection between the high pressure cylinder and the low pressure cylinder at the base were rigid, that is to say, if the opening in the lateral projection from'the base of the low pressure cylinder were not elongated transversely, the lower end of the high pressure cylinder being cooler than the upper end would not move as far away from the low pressure cylinder as the explosion end would move, and. hence the axial line of the high pressure cylinder would not remain parallel to that of the low pressure cylinder. Therefore, in order to maintain the parallelism and prevent buckling of the high pressure cylinder, the flange 57 of the low pressure cylinder has an elongated apertiu-e to permit the required movement of the crank case end, or lower end of the high pressure cylinder. Of course, in practice, the relative movement is very slight, but enough to cause trouble if some provision is not made to take care of it. Each low pressure cylinder also 'has a head projection 59 to receive the head 60 of a high pressure cylinder. The projection 59 may have an air or water jacket space 61, if desired.

The high pressure cylinders are held in place by rods 62 that, pass through lugs 63-64, the lower 611dS 1;i1f-' which high presvalve 15, are ful'crumed, and to which the levers 69 that actuate the exhaust valves 12 are pivoted.

Each lever 68'69 has a ball end' 707 1 respectively to which the valve rods 72-73 respectively connect. Each rod 72 joins through a strengthening web 74 with a strap 75 in which the eccentric 76 works, while the rod 73 joins at 77 to the strap 75 at the bottom of the web 74. In practice there will be an eccentric 76 at each end of'the crank shaft and on each eccentric there will be two bands or straps 75, one for one unit at one side, and the other for the opposite unit, etc., as will be readily understood by reference to Figs. 1 and 2 of the drawings.

In practice the engine may be built of a single unit or several units according to the work to which it is to be put. The engine as illustrated in the drawings is designed to be used as an aviation engineer for use in automobiles and is composed of two sets of units or four units in all. The'units of one set are held at right anglesto those of the other set and only one set of cranks is employed to both sets of units. In other words the connecting rods 49 for the pistons 17 of the cylinders 3 and 8 join to the same crank; the eonnectin rods 48 for the pistons 16 of the cylintfers 1 and 6 join to a common crank 45 and so on, as indicated in Figs. 2 and 3 of the drawings.

In order to render the operation of the valve opening levers 6869 as noiselessv as possible, I may employ what I term hushers best shown in Fig. 4 of the drawings, by reference to which it will be seen that the hushers each consist 'of a curved bar 79 having an aperture to receive a stud 78 on the valve lever 68 or 69, as the case'inay be. The bar 78 rests on the valve stem lever and has rolling contact with the valve lever, a stud 80 being screwed in to the lever 68 or 69 and passing through a holein the valve bar 78 which carries a nut- 82 and a coil spring 83 whereby the bar 78 is held in contact with the valve lever and also with the valve stem.

Having thus described generally the construction of my engine, the mode of operation will be best explained as follows: As sumo the parts to be in the position shown in Fig. 7; the cylinder 3 is filled with charge of burned mixturethat has been drawn in from the cylinder 1, together with a charge ofcold air previously forced into the cylinder, by the pump 19 that is located over the cylinder-4i This chargawhen the piston 17 of'cylinder'3 is in the position shown,

is at about atmospheric pressure. The valve 12 of cylinder 3 is just about to open; the valve 15 of cylinder 1 has been closed for a period of about 5, the ports 18 of cylinder 1' have just been covered by the piston theports 34.-35'are just about to communicate with-one another; air is in the cylinder 1 havingbeen drawn into cylinder 1 by the piston-l7 during the preceding 80 of movement of the piston 17 before the-valve 15 of cylinder 1 is-closed; a charge of compressed new working agent is in cylinder 5 below the piston 30 and a charge of new working agent is being drawn into the cylinder 5 above the piston 30; an exploded charge is in cylinder 2 driving its piston downwardly; the valve 15 of cylinder 2 is within 10 of its opening position; cylinder 4 has a compressed charge of fresh air and old charge residue ahead of it and its valve- 12 has been closed for 60; a compressed- 'charge of air passed into cylinder 4 via duct 24, when the piston 17 thereof was (50 from its upper stroke limit and just after the valve 12 of the cylinder 4 closed. The other engine section will be operating under a similar cycle but in advance and a detail description of its operation is thought to be superfluous.

Now let the parts move 45 from the position shown in Fig. 7 to the position shown in Fig. 8. At this time the valve 12 of cylinder 3 will beopen and the piston 17 will be forcing the exhaust out of the cylinder the valve 15 of cylinder 1 will be closed and the piston 16 of cylinder 1 will be compressing a new charge which has just been admitted from the pump 5 through the ports 34, 35 and 38; the other pump 19 over cylinder 3 will be drawing in a fresh'supply of air throughport 28; the piston 30 of fuel pump 5 will be at the lower limit of its stroke; the piston 16 of cylinder 2 will be still moving downwardly under the influence of the exploded charge in cylinder 2; the valve 15 of cylinder 2 will be open and the piston 17 of cylinder 4 will also be moving downwardly under the influence of the exploded new charge, as well as the old residue charge, and the air that has entered cylinder 4 from pump 19 over cylinde 3 (both cylinders 2 and 4 being at this time in communication); the valve 12 of c vlinder 4 will be closed; the pump 19 over rylinder 4 will be compressing a new charge of air for cylinder 1.

Now let the parts move another 45 from the position shown in Fig. 8 to that shown in Fig. 9. The valve 12 of cylinder 3 will still be open and the piston 17 will still be moving on its exhausting stroke: the valve 15 of cylinder 1 will be closed and a new charge is being compressed ahead of piston 16 in cylinder 1; the pump 19 and cylinder 3 is drawing in a new charge of air through the port 28; the fuel pump 5 is drawing in a new charge of fuel below the piston 30 and compressing a new charge of fuel above the same; the valve 15 of cylinder 2 is open and the piston 16 in cylinder 2 is still moving downwardly on its working stroke as is also the piston 17 of cylinder 4 (both cylinders 2 and 4 being in communication) the valve 12 of cylinder 4 remains closed; the pump 19 over cylinder'4 is still compressing a new charge of air beneath the piston 20 thereof.

Now let the parts move 30 from the position shown in Fig. 8 to the position shown in Fig. 10; the valve 12 of cylinder 3 will have just closed; a charge of air from the pump 19 over cylinder 4 will enter cylinder 3 and-piston 17 will now compress the air and the remainder of the exhaust in cylinder 3; the valve 15 of cylinder 1 will still be closed and the piston 16 of cylinder 1 will still .be compressing; the piston 16 of cylinder 2 will be within 10 from the lower limit of its stroke and the ports 18 of cylinder 2 are being opened to permit the piston17 of cylinder 4 to draw out the old charge from the cylinder 2 through the valve 15 and draw air into the cylinder 2 through ports 18; the valve 15 of cylinder 2 will still be open; the valve12 of cylinder 4 will he closed; the piston 17 of cylinder 4 is still moving downwardly; the pump 19 over cylinder 3 isstill drawing in a new char e; and the pump 19 of the cylinder 4 is still compressing a charge of air.

Now assume the parts to have reached the position shown in Fig. 11 which position is 180 from the position shown in Fig. 7 or after the parts have moved through one half their cycle of operation from the position shown in Fig. 7; the piston 17 of the cylinder 3 will have reached the limit of its up stroke and compressed the charge of fresh air, plus the residue of old charge, ahead of it; the valve 12 of cylinder 4 will be closed; the pump 19 over the cylinder 3 will have drawn in a new charge of air below its piston 20; the valve 15 of cylinder 1 will be closed and the piston 16 of cylinder 1 will be moving downwardly under the influence of the exploded charge; the piston 16 of the cylinder 2 will have recovered the ports 18 thereof, and be moving on its up stroke; the piston 1.7 of the cylinder 4 will have reached the limit of its down stroke and will have drawn the old charge from the cylinder 2 into the cylinder 4 and drawn air intothe cylinder 2 through its ports 18 before the piston closed the same and before the valve 15 of the cylinder 2 is closed; the valve 15 of the cylinder 2 has been closed for 5; the 4 valve 12 of the cylinder 4 is just about to open; the fuel pump ports 32 and 36 are about tocommunicate with one another to permit the fuel pump to inject the fuel into the cylinders 2, the compressed chargr of fuel being above the piston 30 in the cylinder 5, which piston is still drawing new fuel into the cylinder 5 below the same; the pump 19 over the cylinder 4 will have forced its charge into the cylinder 3 and reached the downward limit of its movement.

Now let the parts move 45 from the position shown in Fig. 11 to the position shown in Fig. 12; the piston 17 of the cylinder 3 will be moving downwardly under the combined influence of the residual old charge plus the air charge plus the nearly ignited charge of fuel, as will also be the piston 16 of the cylinder 1; the valve 15 of cylinder 1 will be open; the valve 12 of cylinder 3 will be closed; the pump 19 over cylinder 3 is compressing air below its piston 20; the fuel pump piston 30 is drawing new charge into the cylinder 5 above it and compressing a charge of fuel below it; the piston 16 of cylinder 2 is compressing a new charge of working agent; the Valve 15 of cylinder 2 is closed; the piston 17 of cylinder4 is exhausting; the valve 12 of cylinder 4 is open; the piston 20 of pump 19 over the cylinder 4 is drawing in a new charge beneath the same.

Now let the partsmove another 45 from the position shown in Fig. 11 back to the position shown in Fig. 7. This completes the cycle of operation and the cycle of operation may then be repeated ad infinitum.

It should be understood of course, that the fuel charge injected into the cylinders 1 and 2 by the pump 5 will be a rich mixture and so proportioned as to give the most effective results when united with the air in the cylinders 1 and 2 and when brought into contact with the air and residual charge in the cylinders 3 and 4during the full working stroke of the pistons 16 and 17 respectively.

I have not shown and described any ignition system, as it is obvious that any of the improved types of ignition may be employed in connection with my engine, and therefore illustration and description of an ignition system is believed to be unnecessary.

"What I claim 1s:

1. The method of operating compound in-.

ternal combustion engines which have high and low pressure cylinders and pistons, which consists in causing the low pressure piston to draw air into the high pressure cylinder after the high pressure piston has completed its working stroke, and simulout of said low pressure cylinder to atmosphere; forcing a, new charge of working agent into said high pressure cylinder before said high pressure piston has completed its compressing stroke; forcing air over the wallsof said high pressure cylinder and into said low pressure cylinder before said new charge is fully compressed and ignited; igniting said new charge and subsequently admitting said ignited charge into communication with said air in said low pressure cylinder to cause both pistons to move as working pistons through a working stroke.

2. The method of operating internal combustion engines of the compound two-cycle type which have high and low pressure cylinders and their pistons; which consists in causing thelow pressure piston to draw air into the high pressure cylinder after the high pressure piston has completed its working stroke, and simultaneously drawing the old charge from said high pressure cylinder into said low pressure cylinder: then causing said high pressure piston to compress said air while said low pressure piston moves on its exhausting stroke to force a part of the old charge outof said low pressure cylinder to atmosphere, then forcing a new charge of working agent into said high pressure cylinder before said high pressure cylinder has completed its compressing stroke, and causing said low pressure piston to compress a residual part of the old charge in said low pressure cylinder; then forcing air into said low pressure cylinder to unite with the residual old charge and to be compressed by said low pressure piston, before said new charge in said high pressure cylinder is fully compressed and ignited; then igniting said new charge in said high pressure cylinder to cause said high pressure piston to start on its working stroke, and permitting said low pressure piston to commence its working stroke under the influence of said compressed air and residual old charge; and subsequently throwing the high and low pressure cylinders into communication to permit the ignited new charge in the high pressure cylinder to unite with the air and residual old charge in the low' pressure cylinder to cause both pistons to move through a part of their working strokes under the influence of the combined charges.

3. In an internal combustion engine, a high pressure cylinder and its piston and a low pressure cylinder and its piston, a fuel charging pump connected with the high pressure cylinder, an air charging pump in communicatit with the low pressure cylinder, an intercomniunicating duct between the two cylinders and a valve for controlling the passage through said duct, an exhaust valve for saidlow pressure cylinder, a crank shaft having cranks set at an angle to one another, connecting rods between the respective cranks and the respective pistons to cause said pistons to move one in advance of the other, means for operating said fuel charging pump at a predetermined time, means for operating said air charging pump at a predetermined time, said high pressure cylinder having piston controlled ports all being arranged that said low pressure piston will draw the contents of said high pressure cylinder out of the same when said duct valve is open and when said high pressure cylinder ports are opened andasimultaneously fill said high pressure cylinder with air to be subsequently compressed by sthe-z. high pressure piston, said low' PIQSSHI'GsPlStQIl operating on its up stroke to exhaustt more or less of the old charge to atmosphere through said exhaust valve when open, and to also compress a part of the contents of said low pressure cylinder as said low pressure piston approaches the limit of its up strokesand after said air charging pump has injected a charge of air into said low pressure cylinder', said duct valve operating means having provisions for opening said duct valve as both pistons move on their'down strokes together to bring both cylinders into communication and thereby permit both pistons to operate as working pistons during a sin'mltaneous part of their down stroke.

4. The method of operating compound internal combustion engines which have high and low pressure cylinders and their pistons, which consists in causing said pistons to move one in advance of the other, and which consist in causing said lowpressure piston to draw the old charge out of the high pressure cylinder at intervals, operate in unison with the high essure piston as a working piston at a su sequent interval, exhaust the old charge at a later interval and compress a residual charge during-a still later interval; and which consists further in forcing fuel into the high pressure cylinder as said high pressure piston is traveling on its compression stroke and thereby co mpress said fuel in said high pressure cylinder, and forcing air over said high pressure cylinder into said low pressure cylinder as said low pressure piston begins the compression portion of its cycle.

5. The method of operating compound internal combustion engines which have high and low pressure cylinders and their pistons, which consists in causing said pistons to move one in advance of the other, and which consists in causing said low pressure piston to draw the old charge out of the high-pres sure cylinder at intervals, operate 1n unison with the high pressure piston as a working piston at a subsequent interval, exhaust the old charge at a later interval and compress a residual charge during a still later interval; and which consists further in forcing fuel into the high pressure cylinder as said high pressure piston is traveling on its'compression stroke and thereby compress said fuel in said high pressure cylinder, and forcing air over said high pressure cylinder into said low pressure cylinder as said low pressure piston begins the compression portion of its cycle, and before said new charge in the high pressure cylinder has been fully compressed and ignited, then igniting said new charge in sand high pressure cylinder and subsequently throwing said cylinders into communication to cause said ignited charge to unite with the'residual charge and airin said low pressurecylinder to impel both pistons during a part of their working stroke.

' 6. In a compound internal combustion engine, a high pressure cylinder and its piston, a low pressure cylinder and its piston, a valved intercommunicating duct between said cylinders, acrank shaft having cranks set at an angle to one another, connecting rods between said cranks and said pistons whereby one of said pistons will move in advance of the other, a valved exhaust port for the low pressure cylinder, piston controlled inlet ports for said high ressure cylinder, valve actuating devices or actuating the valve in said exhaust port and for actuating the valve in said intercommunicating port, a fuel pump including a cylinder and piston, said crank shaft having a crank for said fuel pump and a connection between said fuel pump and said last named crank, a duct between-said fuel pump and said high pressure cylinder, said fuel pump cylinder having a piston controlled port for said duct, said fuel pump being set to open the port into said fuel duct after said high pressure piston has commenced its compression stroke, and means for forcing air over the high pressure ylinder walls into said low pressure cylinder to draw the heat from said high pressure cylinder-Walls and convey it into said low pressure cylinder at predetermined times.

7. Ina compound internal combustion engine, a high pressure cylinder and its piston, a low pressure cylinder and its piston, a valved intercommunicating duct between 1 said cylinders, a crank shaft having cranks set at an angle to one another, connecting rods between said cranks and said pistons whereby one of said pistons will move in advance of the other, a valved exhaustport for the low pressure cylinder, piston controlled inlet ports for said high pressure cylinder, valve actuating devices for actuating the valve in said exhaust port and for actuating the valve in said intercommuni- 'cating (port, a fuel pump including a cylinder an piston, said crank shaft havinga crank for said fuel pump and a connection between said fuel pump and said last named crank, a duct between said fuel pump and saidhigh pressure cylinder, said fuel pump cylinder having a piston controlled port for said duct, said .fuel duct being set to 0 )en the port into said fuel duct after said big 1 pressurepiston has commenced its compression stroke, and means for forcing air over the high pressure cylinder walls into said low pressure cylinder to draw the heat from said high pressure walls and convey itinto said low pressure cylinder before the high pressure piston has completed its compression stroke and before the new charge has been ignited.

8. In an internal combustion engine, two double units, one set to operate 90 in advance of the other and each of said sets including a pair of high pressure cylinders and their pistons and a pair of low pressure cylinders and their pistons, a crank shaft with which all of said pistons are connected, the high pressure piston of each unit operating in advance of the low pressure piston of the same unit, each set of units including a common double acting fuel pump connected with the crank shaft and having fuel ducts to the respective high pressure cylinders, said fuel pump including piston controlled ports in each of said ducts which are'arranged to open as the pump piston' reaches the limit of its strokes, a duct between the high'pressure cylinder and the low pressure cylinder of the respective unit,

between each air pump and the respective low pressure cylinder, said air pumps each including a piston controlled port communicating with the respective duct,- theair pumps being designed to inject air into the respective low pressure cylinders during the exhausting stroke of thelow pressure piston and the exhaust valves of said low pressure cylinders being designed to close just prior to the admission of air from the air pump into the respective low pressure cylinder.

' 9. In an internal combustion engine, a crank case, a low pressure cylinder relatively fixedly secured to the crank case, said low pressure cylinder having a laterally pro ject'ed member at its head and having a laterally projected member at its base, said laterally projected members having alining passages, a high pressure cylinder held in said passages and substantially parallel with said low pressure cylinder, said base projee tion passage of said low pressure cylinder and valved ports and ducts between said being elongated to allow for the movement cylinders and means for controlling the of saidhigh pressure, cylinder toward or same.

from said low pressure cylinder in expand- WM. J-. WRIGHT.

5 ing and contracting, pistons operating in Witnesses:

sald cylinders, a crank shaft and connecting 'A. E. DIETERICH, rods between said crank shaft and pistons, FRED G. DIETERIGH. 

